A Calibration Method for RF and Microwave Noise Sources

Uncertainties in noise-figure and noise-parameter measurements depend to a large degree on the accuracy with which noise sources are calibrated. In some cases, the uncertainties are similar to measured quantities. This paper discusses a method for calibration of RF and microwave noise sources against a reference noise source. This method takes into account noise parameters of the receiver used for noise power measurements and includes temperature corrections to account for both drifts in the ambient temperature and heat transfer between the receiver and noise sources. Experimental results demonstrate the feasibility of the proposed method. As estimated with a Monte Carlo analysis, a uncertainty of 0.046 dB for a 5-dB excess-noise-ratio (ENR) noise source is obtained with the proposed method. This uncertainty is approximately one third of ENR uncertainties reported for commercial noise sources.